Moving picture transmission apparatus, moving picture reception apparatus, and moving picture data record medium

ABSTRACT

In a moving picture data structure having a structure comprising I pictures (intraframe coded image) and P pictures (interframe forward predictive coded image), a P′ picture of a forward predictive coded image of a picture immediately preceding an I picture and the I picture is placed following the I picture. If an error occurs during the I picture transmission, the P′ picture can be used to recover from the error.

BACKGROUND OF THE INVENTION

[0001] This invention relates to error recovery at the moving picturetransmission time in a network where an error is not negligible.

[0002] Hitherto, a method wherein a moving picture transmissionapparatus provides redundant data for error recovery and when an erroroccurs in a moving picture reception apparatus, the redundant data isused to recover from the error has been known as an error recoverymethod applied when moving picture data stored in the moving picturetransmission apparatus is transferred to the moving picture receptionapparatus over a transmission line.

[0003] Generally, moving picture data can be assumed to consist of aplurality of still images successive in time sequence. In an MPEG imagecompression technique, the moving picture data consists of I picture(intraframe coded image), P picture (interframe forward predictive codedimage), and B picture (bidirectional predictive coded image), andredundancy in the time direction of the moving picture data is reduced.To enable a random jump, an I picture appears periodically. Such astructure is useful for a system such as a VOD (video on demand) system.

[0004]FIG. 10 shows an example of a system using an error recoverymethod in moving picture transmission in a related art. A moving picturetransmission apparatus 1001 comprises network interface means. 1004,data transmission means 1005, data reception means 1006, moving picturesupply means 1007 for supplying a moving picture, moving picture dataacquisition means 1008 for acquiring object data, and redundant dataaddition means 1016 for adding redundant data. A moving picturereception apparatus 1002 comprises network interface means 1009, datatransmission means 1011, data reception means 1012, input means 1010 formaking a request for the reproduction state of a moving picture, errordetermination means 1013 for determining an error, decoding means 1014for decoding moving picture data into a format in which the movingpicture data can be displayed, and display means 1015 for displaying amoving picture.

[0005] In the system, when the user enters a command through the inputmeans 1010 of the moving picture reception apparatus 1002, the commandis sent through the data transmission means 1011, the network interfacemeans 1009, a transmission line 1003, the network interface 1004 of themoving picture transmission apparatus 1001, and the data reception means1006 to the moving picture data acquisition means 1008, which thenacquires objective moving picture data from the moving picture supplymeans 1007 in accordance with the command. The redundant data additionmeans 1016 adds redundant data to the acquired moving picture data so asto send all frames or I pictures doubly. Then, the resultant data issent through the data transmission means 1005, the network interfacemeans 1004, the transmission line 1003, the network interface means 1009of the moving picture reception apparatus 1002, and the data receptionmeans 1012 to the error determination means 1013 for detecting an errorduring the transmission of the data. If an error does not occur, theerror determination means 1013 sends the moving picture data to thedecoding means 1014 and the redundant moving picture data is discarded.If an error occurs, the redundant data is sent to the decoding means1014. The decoding means 1014 decodes the coded moving picture data intodisplayable form and sends the provided data to the display means 1015,which then displays a moving picture based on the data.

[0006] To use the system to add redundant data so as to send all framesdoubly, the transmitted data amount is doubled; to add redundant data soas to send I pictures doubly, the transmitted data amount result inabout a 1½-times amount because the I picture occupation percentagebetween one I picture and the next I picture is about a half.

[0007] To transmit a moving picture on a narrow-band transmission linein the error recovery method in moving picture transmission in therelated art, the effective band is furthermore narrowed because of theredundant data and the moving picture quality and the frame rate arelowered; this is a problem.

SUMMARY OF THE INVENTION

[0008] It is therefore an object of the invention to enable errorrecovery using additional data with smaller redundancy in order to use aband of a transmission line efficiently in an error recovery method inmoving picture transmission.

[0009] To the end, according to the invention, first, a moving picturedata structure wherein a P′ picture of a forward predictive coded imageof a picture immediately preceding an I picture (intraframe coded image)and the I picture is placed preceding or following the I picture isprovided.

[0010] Thus, if an error occurs in the I picture during the datatransmission, the P′ picture can be used to recover the I picture fromthe error.

[0011] Second, a moving picture data structure wherein a P″ picture of aforward predictive coded image of an I picture immediately preceding thecurrent I picture and the current I picture is placed preceding orfollowing the current I picture is provided.

[0012] Thus, if an error occurs in the I picture or the pictureimmediately preceding the I picture during the data transmission, theimmediately preceding I picture and the P″ picture can be used torecover the I picture from the error.

[0013] Third, a moving picture transmission apparatus comprisesdifferential data transmission means for transmitting data for errorcorrection on a different band when moving picture data is transmittedto a transmission line.

[0014] Thus, differential data can be transmitted without changing datatransmission means.

[0015] Fourth, a moving picture transmission apparatus comprises timeinformation addition means for adding the same time information asmoving picture data to data for error correction when the moving picturedata is transmitted to a transmission line.

[0016] Thus, the moving picture data reception apparatus receiving themoving picture data can separate the received data into the movingpicture data and the data for error correction.

[0017] Fifth, a moving picture transmission apparatus comprisesredundancy control data reception means for receiving redundancy controldata from moving picture reception apparatus when the moving picturedata is transmitted to a transmission line.

[0018] Thus, data for error correction can be optimized fortransmission.

[0019] Sixth, a moving picture reception apparatus comprisesdifferential data reception means for receiving data for errorcorrection on a different band when moving picture data is received froma transmission line.

[0020] Thus, differential data can be received without changing datareception means.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In the accompanying drawings:

[0022]FIG. 1 is a drawing to show moving picture data structures in afirst embodiment of the invention;

[0023]FIG. 2 is a block diagram to show the configuration of a movingpicture transmission system in the first embodiment of the invention;

[0024]FIG. 3 is a drawing to show moving picture data structures in asecond embodiment of the invention;

[0025]FIG. 4 is a block diagram to show the configuration of a movingpicture transmission system in the second embodiment of the invention;

[0026]FIG. 5 is a drawing to show moving picture data structures in athird embodiment of the invention;

[0027]FIG. 6 is a block diagram to show the configuration of a movingpicture transmission system in the third embodiment of the invention;

[0028]FIG. 7 is a drawing to show moving picture data structures in afourth embodiment of the invention;

[0029]FIG. 8 is a block diagram to show the configuration of a movingpicture transmission system in the fourth embodiment of the invention;

[0030]FIG. 9 is a block diagram to show the configuration of a movingpicture transmission system in a fifth embodiment of the invention; and

[0031]FIG. 10 is a block diagram to show the configuration of a movingpicture transmission system in a related art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] Referring now to the accompanying drawings (FIGS. 1 to 9), thereare shown preferred embodiments of the invention. As many apparentlywidely different embodiments of the invention may be madewithout-departing from the spirit and scope thereof, it is to beunderstood that the invention is not limited to specific embodimentsthereof.

First Embodiment

[0033]FIG. 1 shows a moving picture data structure. In the figure, Idenotes an I picture (intraframe coded image), P denotes a P picture(interframe forward predictive coded image), and P′ denotes a P′ picture(forward predictive coded image of “a picture [S] immediately precedingone I picture [T]” and “the I picture [T]”).

[0034]FIG. 2 is a block diagram to show the configuration of an errorcorrection system. In the figure, numeral 201 denotes a moving picturetransmission apparatus and numeral 202 denotes a moving picturereception apparatus; they are connected by a transmission line 203.

[0035] The moving picture transmission apparatus 201 has networkinterface means 204, data transmission means 205, data reception means206, and moving picture data supply means 207 for supplying a movingpicture. Moving image data acquisition means 208 acquires moving picturedata based on command data obtained from the data reception means 206from the moving picture data supply means 207. Differential datacalculation means 216 calculates a P′ picture of a forward predictivecoded image of a picture immediately preceding an I picture and the Ipicture, time information addition means 217 adds time information, anddifferential data addition means 218 adds the P′ picture following the Ipicture.

[0036] The moving picture reception apparatus 202 has network interfacemeans 209, data transmission means 211, data reception means 212, inputmeans 210 for entering a command, and display means 215 for displaying amoving picture. Redundant data separation means 219 uses timeinformation to separate data obtained at the data reception means 212into moving picture data and redundant data. Error determination means213 checks whether or not an error occurs during the transmission of thedata, error recovery means 220 executes error recovery, decoding means214 decodes the data, and display means 215 displays the data.

[0037] The operation of the described data transmission system is asfollows:

[0038] When the operator enters a moving picture command such asplayback, stop, fast forward, rewind, or random access, the input meansof the moving picture reception apparatus 202 sends the entered commandto the data transmission means 211. The command sent to the datatransmission means 211 is received by the data reception means 206 ofthe moving picture transmission apparatus 201 through the networkinterface means 209, the transmission line 203, and the networkinterface means 204. The command received by the data reception means206 is sent to the moving picture data acquisition means 208, which thenacquires the moving picture data corresponding to the command from themoving picture data supply means 207.

[0039] The moving picture data acquired by the moving picture dataacquisition means 208 is sent to the differential data calculation means216, which then calculates and prepares a P′ picture of a forwardpredictive coded image of a picture immediately preceding an I pictureand the I picture. The time information addition means 217 adds the sametime information as the I picture to the prepared P′ picture. Thedifferential data addition means 218 inserts the P′ picture followingthe I picture. The data transmission means 205 adds network informationto the moving picture data and transmits the resultant data to thetransmission line 203 through the network interface 204.

[0040] The moving picture data in which the P′ picture is inserted isreceived by the data reception means 212 through the transmission line203 and the network interface 209. The redundant data separation means219 separates the received moving picture data into moving picture dataand redundant data (P′ picture) and sends them to the errordetermination means 213. The error determination means 213 checkswhether or not an error occurs based on the time information added bythe time information addition means 217 and the network informationadded by the data transmission means 205, then sends the moving picturedata to the error recovery means 220. If an error occurs at the Ipicture read time, the error recovery means 220 uses the P′ picture sentfollowing the I picture in place of the error occurring I picture andsends the data to the decoding means 214. If an error occurs at theframe read time other than the I picture, the error recovery means 220discards the data until another I picture is sent. If an error does notoccur, the error recovery means 220 discards the P′ picture. Thedecoding means 214 decodes the moving picture data into a format inwhich the display means 215 can display the moving picture data, thenthe display means 215 displays a moving picture.

[0041] In the related art, to add redundant data so as to send allframes doubly, the transmitted data amount is doubled; to add redundantdata so as to send I pictures doubly, the transmitted data amount resultin about a 1.5-times amount because the I picture occupation percentagebetween one I picture and the next I picture is about a half.

[0042] In the embodiment, however, when an error occurs in an I pictureduring the data transmission, the P′ picture (forward predictive codedimage of the picture immediately preceding the I picture and the Ipicture) sent following the I picture is used, so that the P′ pictureoccupation percentage between the I picture and the next I picturebecomes about a seventh (at the time of two frames per second); movingpicture error recovery can be executed with a less data amount and thepractical effect is large

Second Embodiment

[0043]FIG. 3 shows a moving picture data structure. In the figure, Idenotes an I picture (intraframe coded image) P denotes a P picture(interframe forward predictive coded image), and P″ denotes a P″ picture(forward predictive coded image of “an I picture [X] immediatelypreceding one I picture [Y]” and “the current I picture [Y]”).

[0044]FIG. 4 is a block diagram to show the configuration of an errorcorrection system. In the figure, numeral 401 denotes a moving picturetransmission apparatus and numeral 402 denotes a moving picturereception apparatus; they are connected by a transmission line 403.

[0045] The moving picture transmission apparatus 401 has networkinterface means 404, data transmission means 405, data reception means406, and moving picture data supply means 407 for supplying movingpicture. Moving image data acquisition means 408 acquires moving picturedata based on command data obtained from the data reception means 406from the moving picture data supply means 407 and temporarily retains Ipictures in basic image retention means 421. Differential datacalculation means 416 calculates a P″ picture of a forward predictivecoded image of the I picture immediately preceding one I picture andthis I picture, time information addition means 417 adds timeinformation, and differential data addition means 418 adds the P′picture following the I picture.

[0046] The moving picture reception apparatus 402 has network interfacemeans 409, data transmission means 407, data reception means 412, inputmeans 410 for entering a command, and display means 415 for displaying amoving picture. Redundant data separation means 419 uses timeinformation to separate data obtained at the data reception means 412into moving picture data and redundant data. Error determination means413 checks whether or not an error occurs during the transmission of thedata, and temporarily retains I pictures in basic image retention means422. Error recovery means 420 executes error recovery, decoding means414 decodes the data, and display means 415 displays the data.

[0047] The operation of the described data transmission system is asfollows:

[0048] When the operator enters a moving picture command such asplayback, stop, fast forward, rewind, or random access, the input meansof the moving picture reception apparatus 402 sends the entered commandto the data transmission means 411. The command sent to the datatransmission means 411 is received by the data reception means 406 ofthe moving picture transmission apparatus 401 through the networkinterface means 409, the transmission line 403, and the networkinterface means 404. The command received by the data reception means406 is sent to the moving picture data acquisition means 408, which thenacquires the moving picture data corresponding to the command from themoving picture data supply means 407.

[0049] The I pictures of the moving picture data acquired by the movingpicture data acquisition means 408 are temporarily retained in the basicimage retention means 421 and others are sent to the differential datacalculation means 416, which then calculates and prepares a P″ pictureof a forward predictive coded image of the I picture immediatelypreceding one I picture and this I picture. The time informationaddition means 417 adds the same time information as the I picture tothe prepared P″ picture. The differential data addition means 418inserts the P″ picture following the I picture. The data transmissionmeans 405 adds network information to the moving picture data andtransmits the resultant data to the transmission line 403 through thenetwork interface 404.

[0050] The moving picture data in which the P″ picture is inserted isreceived by the data reception means 412 through the transmission line403 and the network interface 409. The redundant data separation means419 separates the received moving picture data into moving picture dataand redundant data (P″ picture) and sends them to the errordetermination means 413. The error determination means 413 checkswhether or not an error occurs based on the time information added bythe time information addition means 417 and the network informationadded by the data transmission means 405, then sends the I pictures tothe basic image retention means 422 and others to the error recoverymeans 420. If an error occurs at the I picture read time, the errorrecovery means 420 uses the P″ picture and the retained I picturecorresponding to the error occurring I picture and sends them to thedecoding means 414 in place of the error occurring I picture. If anerror occurs at the frame read time other than the I picture, the errorrecovery means 420 discards the data until another I picture is sent. Ifan error does not occur, the error recovery means 420 discards the P″picture. The decoding means 414 decodes the moving picture data into aformat in which the display means 415 can display the moving picturedata, then the display means 415 displays a moving picture.

[0051] Thus, in the embodiment, if an error occurs in an I picture orits immediately preceding picture during the data transmission, the P″picture (forward predictive coded image of the I picture immediatelypreceding one I picture and this I picture), whereby moving pictureerror recovery without waste as in the related art can be executed as inthe first embodiment, and the practical effect is large.

[0052] Comparing the P′ picture in the first embodiment with the P″picture in the second embodiment, to use the P′ picture, an errorcorrection can be made without providing the basic image retention meansand the effect is exerted at smaller costs; on the other-hand, to usethe P″ picture, the basic image retention means is provided, whereby ifan error occurs in the frame immediately preceding an I picture, theeffect is exerted.

Third Embodiment

[0053]FIG. 5 shows a moving picture data structure. In the figure, Idenotes an I picture (intraframe coded image), P denotes a P picture(interframe forward predictive coded image), and P′ denotes a P′ picture(forward predictive coded image of “a picture [S] immediately precedingone I picture [T]” and “the I picture [T]”). The P′ picture uses adifferent band from that of the normal moving picture data.

[0054]FIG. 6 is a block diagram to show the configuration of an errorcorrection system. In the figure, numeral 601 denotes a moving picturetransmission apparatus and numeral 602 denotes a moving picturereception apparatus; they are connected by a transmission line 603.

[0055] The moving picture transmission apparatus 601 has networkinterface means 604, data transmission means 605, data reception means606, and moving picture data supply means 607 for supplying a movingpicture. Moving image data acquisition means 608 acquires moving picturedata based on command data obtained from the data reception means 606from the moving picture data supply means 607. Differential datacalculation means 616 calculates a P′ picture of a forward predictivecoded image of a picture immediately preceding an I picture and the Ipicture, the information addition means 617 adds time information anddifferential data transmission means 618 transmits the P′ picture to thetransmission line 603 through the network interface means 604.

[0056] The moving picture reception apparatus 602 has network interfacemeans 609, data transmission means 611, data reception means 612, inputmeans 610 for entering a command, and display means 615 for displaying amoving picture. Error determination means 613 checks data obtained atthe data reception means 612 and differential data reception means 619for an error occurring during the transmission of the data, errorrecovery means 620 executes error recovery, decoding means 614 decodesthe data, and display means 615 displays the data.

[0057] The operation of the described data transmission system is asfollows:

[0058] When the operator enters a moving picture command such as playback, stop, fast forward, rewind, or random access, the input means ofthe moving picture reception apparatus 602 sends the entered command tothe data transmission means 611. The command sent to the datatransmission means 611 is received by the data reception means 606 ofthe moving picture transmission apparatus 601 through the networkinterface means 609, the transmission line 603, and the networkinterface means 604. The command received by the data reception means606 is sent to the moving picture data acquisition means 608, which thenacquires the moving picture data corresponding to the command from themoving picture data supply means 607.

[0059] The moving picture data acquired by the moving picture dataacquisition means 608 is sent to the differential data calculation means616, which then calculates and prepares a P′ picture of a forwardpredictive coded image of a picture immediately preceding an I pictureand the I picture. The time information addition means 617 adds the sametime information as the I picture to the prepared P′ picture. Thedifferential data transmission means 618 sends the P′ picture to thetransmission line 603 through the network interface means 604 and thedata transmission means 605 sends others to the transmission line 603through the network interface 604.

[0060] The P′ picture and the moving picture data are received by thedifferential data reception means 619 and the data reception means 612through the transmission line 603 and the network interface 609, thenare sent to the error determination means 613. The error determinationmeans 613 checks whether or not an error occurs based on the timeinformation added by the time information addition means 617 and thenetwork information added by the data transmission means 605, then sendsthe moving picture data to the error recovery means 620. If an erroroccurs at the I picture read time, the error recovery means 620 uses theP′ picture in place of the error occurring I picture and sends the datato the decoding means 614. If an error occurs at the frame read timeother than the I picture, the error recovery means 620 discards the datauntil another I picture is sent. If an error does not occur, the errorrecovery means 620 discards the P′ picture. The decoding means 614decodes the moving picture data into a format in which the display means615 can display the moving picture data, then the display means 615displays a moving picture.

[0061] Thus, in the embodiment, with the moving picture datatransmission means and reception means intact as in the related art,when an error occurs in an I picture during the data transmission, theP′ picture of a forward predictive coded image of the pictureimmediately preceding the I picture and the I picture sent from anotherband can be used to execute moving picture error recovery, and thepractical effect is large.

[0062] Comparing insertion of the P′ picture in moving picture data inthe first embodiment with transmission of the P′ picture on another bandin the third embodiment, in the insertion method of the P′ picture inmoving picture data, the redundant data addition means and the redundantdata separation means make error corrections, so that the effect isexerted without providing new transmission means or new reception means;on the other hand, in the transmission method of the P′ picture onanother band, the transmission apparatus and the reception apparatus forthe P′ picture are provided in place of the redundant data separationmeans, whereby the effect is exerted with the transmission means and thereception means intact as in the related art.

Fourth Embodiment

[0063]FIG. 7 shows a moving picture data structure. In the figure, Idenotes an I picture (intraframe coded image), P denotes a P picture(interframe forward predictive coded image), and P″ denotes a P″ picture(forward predictive coded image of “an I picture [X] immediatelypreceding one I picture [Y]” and “the current I picture [Y]”). The P″picture uses a different band from that of the moving picture data inthe related art.

[0064]FIG. 8 is a block diagram to show the configuration of an errorcorrection system. In the figure, numeral 801 denotes a moving picturetransmission apparatus and numeral 802 denotes a moving picturereception apparatus; they are connected by a transmission line 803.

[0065] The moving picture transmission apparatus 801 has networkinterface means 804, data transmission means 805, data reception means806, and moving picture data supply means 807 for supplying a movingpicture. Moving image data acquisition means 808 acquires moving picturedata based on command data obtained from the data reception means 806from the moving picture data supply means 807 and temporarily retains Ipictures in basic image retention means 821. Differential datacalculation means 816 calculates a P″ picture of a forward predictivecoded image of the I picture immediately preceding one I picture andthis I picture, time information addition means 817 adds timeinformation, and differential data transmission means 818 transmits theP′ picture to the transmission line 803 through the network interfacemeans 804.

[0066] The moving picture reception apparatus 802 has network interfacemeans 809, data transmission means 811, data reception means 812, inputmeans 810 for entering a command, and display means 815 for displaying amoving picture. Error determination means 813 checks data obtained atthe data reception means 812 and differential data reception means 819for an error occurring during the transmission of the data, andtemporarily retains I pictures in basic image retention means 822. Errorrecovery means 820 executes error recovery, decoding means 814 decodesthe data, and display means 815 displays the data.

[0067] The operation of the described data transmission system is asfollows:

[0068] When the operator enters a moving picture command such as playback, stop, fast forward, rewind, or random access, the input means ofthe moving picture reception apparatus 802 sends the entered command tothe data transmission means 811. The command sent to-the datatransmission means 811 is received by the data reception means 806 ofthe moving picture transmission apparatus 801 through the networkinterface means 809, the transmission line 803, and the networkinterface means 804. The command received by the data reception means806 is sent to the moving picture data acquisition means 808, which thenacquires the moving picture data corresponding to the command from themoving picture data supply means 807.

[0069] The I pictures of the moving picture data acquired by the movingpicture data acquisition means 808 are temporarily retained in the basicimage retention means 821 and others are sent to the differential datacalculation means 816, which then calculates and prepares a P″ pictureof a forward predictive coded image of the I picture immediatelypreceding one I picture and this I picture. The time informationaddition means 817 adds the same time information as the I picture tothe prepared P″ picture. The differential data transmission means 818sends the P″ picture to the transmission line 803 through the networkinterface means 804 and the data transmission means 805 sends others tothe transmission line 803 through the network interface 804.

[0070] The P″ picture and the moving picture data are received by thedifferential data reception means 819 and the data reception means 812through the transmission line 803 and the network interface 809, thenare sent to the error determination means 813. The error determinationmeans 813 checks whether or not an error occurs based on the timeinformation added by the time information addition means 817 and thenetwork information added by the data transmission means 805, then sendsthe I pictures to the basic image retention means 822 and others to theerror recovery means 820. If an error occurs at the I picture read time,the error recovery means 820 uses the P″ picture and the retained Ipicture corresponding to the error occurring I picture and sends them tothe decoding means 814 in place of the error occurring I picture. If anerror occurs at the frame read time other than the I picture, the errorrecovery means 820 discards the data until another I picture is sent. Ifan error does not occur, the error recovery means 820 discards the P″picture. The decoding means 814 decodes the moving picture data into aformat in which the display means 815 can display the moving picturedata, then the display means 815 displays a moving picture.

[0071] Thus, in the embodiment, with the moving picture datatransmission means and reception means intact as in the related art,when an error occurs in an I picture during the data transmission, theP″ picture of a forward predictive coded image of I the pictureimmediately preceding the I picture and the I picture sent from anotherband can be used to execute moving picture error recovery, and thepractical effect is large.

[0072] Comparing insertion of the P″ picture in moving picture data inthe second embodiment with transmission of the P″ picture on anotherband in the fourth embodiment, in the insertion method of the P″ picturein moving picture data, the redundant data addition means and theredundant data separation means make error corrections, so that theeffect is exerted without providing new transmission means or newreception means; on the other hand, in the transmission method of the P″picture on another band, the transmission apparatus and the receptionapparatus for the P″ picture are provided in place of the redundant dataseparation means, whereby the effect is exerted with the transmissionmeans and the reception means intact as in the related art.

Fifth Embodiment

[0073]FIG. 9 is a block diagram to show the configuration of an errorcorrection system. In the figure, numeral 901 denotes a moving picturetransmission apparatus and numeral 902 denotes a moving picturereception apparatus; they are connected by a transmission line 903.

[0074] The moving picture transmission apparatus 901 has networkinterface means 904, data transmission means 905, data reception means906, and moving picture data supply means 907 for supplying a movingpicture. Moving image data acquisition means 908 acquires moving picturedata based on command data obtained from the data reception means 906from the moving picture data supply means 907. Differential datacalculation means 916 calculates a P′ picture of a forward predictivecoded image of a picture immediately preceding an I picture and the Ipicture, time information addition means 917 adds time information, anddifferential data addition means 918 determines the frequency addedfollowing the I picture based on redundancy data provided by redundancydata reception means 921.

[0075] The moving picture reception apparatus 902 has network interfacemeans 909, data transmission means 911, data reception means 912, inputmeans 910 for entering a command, and display means 915 for displaying amoving picture. Redundant data separation means 919 uses timeinformation to separate data obtained at the data reception means 912into moving picture data and redundant data. Error determination means913 checks whether or not an error occurs during the transmission of thedata, redundancy data transmission means 922 sends the error frequencyto the moving picture transmission apparatus 901, error recovery means920 executes error recovery, decoding means 914 decodes the data, anddisplay means 915 displays the data.

[0076] The operation of the described data transmission system is asfollows:

[0077] When the operator enters a moving picture command such as playback, stop, fast forward, rewind, or random access, the input means ofthe moving picture reception apparatus 902 sends the entered command tothe data transmission means 911. The command sent to the datatransmission means 911 is received by the data reception means 906 ofthe moving picture transmission apparatus 901 through the networkinterface means 909, the transmission line 903, and the networkinterface means 904. The command received by the data reception means906 is sent to the moving picture data acquisition means 908, which thenacquires the moving picture data corresponding to the command from themoving picture data supply means 907.

[0078] The moving picture data acquired by the moving picture dataacquisition means 908 is sent to the differential data calculation means916, which then calculates and prepares a P′ picture of a forwardpredictive coded image of a picture immediately preceding an I pictureand the I picture. The time information addition means 917 adds the sametime information as the I picture to the prepared P′ picture. Thedifferential data addition means 918 obtains the error occurrencefrequency information in the moving picture reception apparatus 902provided by the redundancy data reception means 921. If an error littleoccurs, the differential data addition means 918 stops inserting the P′picture; if an error occurs frequently, the differential data additionmeans 918 inserts the P′ picture following the I picture. The datatransmission means 905 adds network information to the moving picturedata and transmits the resultant data to the transmission line 903through the network interface 904.

[0079] The moving picture data in which the P′ picture is inserted isreceived by the data reception means 912 through the transmission line903 and the network interface 909. The redundant data separation means919 separates the received moving picture data into moving picture dataand redundant data (P′ picture) and sends them to the errordetermination means 913. The error determination means 913 checkswhether or not an error occurs based on the time information added bythe time information addition means 917 and the network informationadded by the data transmission means 905, then sends the moving picturedata to the error recovery means 920 and sends the error occurrencefrequency to the redundancy data transmission means 922, which thensends the error occurrence frequency to the moving picture transmissionapparatus 901. If an error occurs at the I picture read time, the errorrecovery means 920 uses the P′ picture sent following the I picture inplace of the error occurring I picture and sends the data to thedecoding means 914. If an error occurs at the frame read time other thanthe I picture, the error recovery means 920 discards the data untilanother I picture is sent. If an error does not occur, the errorrecovery means 920 discards the P′ picture. The decoding means 914decodes the moving picture data into a format in which the display means915 can display the moving picture data, then the display means 915displays a moving picture.

[0080] Thus, in the embodiment, when an error occurs in an I pictureduring the data transmission, the P′ picture of a forward predictivecoded image of the picture immediately preceding the I picture and the Ipicture sent following the I picture is used and the redundancy data istransmitted, whereby optimum moving picture error recovery can beexecuted and the practical effect is large.

[0081] The embodiment can be incorporated not only in the P′ pictureinsertion method, but also in the P″ picture insertion method (secondembodiment) and the transfer methods of P′ and P″ redundant data ondifferent bands (third and fourth embodiments).

[0082] In the invention, the examples wherein the P′ and P″ pictures areinserted immediately following the I picture have been described, butthe P′ or P″ picture may be inserted immediately preceding the Ipicture. If a picture loss occurs, for example, in n successive frames,it is also possible to insert the P′ or P″ picture into the (n+1)stframe preceding or following the I picture rather than immediatelypreceding or following the I picture.

[0083] In the above description, it is explained transmission andreception of the moving picture data which has a data structureaccording to the present invention between the moving picturetransmission apparatus and the moving picture reception apparatusaccording to the present invention. However, the present invention isnot limited thereto. Transmission and reception of the moving picturecan be performed between the standard moving picture transmissionapparatus and the moving picture reception apparatus of the presentinvention, or between the moving picture transmission apparatus of thepresent invention and the standard moving picture reception apparatus.

[0084] In a case of that the moving picture transmission apparatus ofthe present invention transmits the moving picture to the standardmoving picture reception apparatus and the standard moving picturereception apparatus playbacks the moving picture, one frame forredundancy/deferential data is increased. However, human eye can notrecognize reproduction of this one frame. Thus, picture quality is notinfluenced.

[0085] Additionally, if an identifier (e.g. time stamp) is added to eachframe in order to prevent the redundant reproduction, only one ofsubsequent P′ or P″ frame (vicinity before or after the I frame, whichis send by the same band with I frame) is reproduced subsequent to Iframe (intraframe).

[0086] On the other hand, in a case of that the standard moving picturetransmission apparatus transmits moving picture and the moving picturereception apparatus of the present invention receives the movingpicture, the reception apparatus of the present invention whicheliminates redundancy data is naturally able to determine the redundantdata is absent. Therefore, usual moving picture data (e.g. MPEG data) isalso able to reproduce.

[0087] The advantages of the invention are as follows:

[0088] First, a moving picture data structure wherein a P′ picture of aforward predictive coded image of a picture immediately preceding an Ipicture (intraframe coded image) and the I picture is placed precedingor following the I picture is provided, so that if an error occurs inthe I picture during the data transmission, the P′ picture can be usedto recover the I picture from the error.

[0089] Second, a moving picture data structure wherein a P″ picture of aforward predictive coded image of an I picture immediately preceding thecurrent I picture and the current I picture is placed preceding orfollowing the current I picture is provided, so that if an error occursin the I picture or the picture immediately preceding the I pictureduring the data transmission, the immediately preceding I picture andthe P″ picture can be used to recover the I picture from the error.

[0090] Third, the moving picture transmission apparatus comprises thedifferential data transmission means for transmitting data for errorcorrection on a different band when moving picture data is transmittedto the transmission line, whereby differential data can be transmittedwithout changing the data transmission means.

[0091] Fourth, the moving picture transmission apparatus comprises thetime information addition means for adding the same time information asmoving picture data to data for error correction when the moving picturedata is transmitted to the transmission line whereby the moving picturedata reception apparatus receiving the moving picture data can separatethe received data into the moving picture data and the data for errorcorrection.

[0092] Fifth, the moving picture transmission apparatus comprises theredundancy control data reception means for receiving redundancy controldata from the moving picture reception apparatus when the moving picturedata is transmitted to the transmission line, whereby data for errorcorrection can be optimized for transmission.

[0093] Sixth, the moving picture reception apparatus comprises thedifferential data reception means for receiving data for errorcorrection on a different band when moving picture data is received fromthe transmission line, whereby differential data can be received withoutchanging the data reception means.

What is claimed is:
 1. A record medium recording moving picture datahaving a structure comprising: I pictures (intraframe coded image); Ppictures (interframe forward predictive coded image); and P′ picturewhich is a forward predictive coded image of a picture immediatelypreceding an I picture and the I picture being placed preceding orfollowing the I picture:
 2. A record medium recording moving picturedata having a structure comprising: I pictures (interframe coded image);P pictures (interframe forward predictive coded image); and P″ picturewhich is a forward predictive coded image of an I picture immediatelypreceding the current I picture and the current I picture being placedpreceding or following the current I picture.
 3. A moving picturetransmission apparatus comprising: moving picture data supply means;moving picture data acquisition means for acquiring objective movingpicture data from said moving picture data supply means; and datatransmission means for transmitting the moving picture data acquired bysaid moving picture data acquisition means to a transmission line; anddifferential data calculation means being placed between said movingpicture data supply means and said data transmission means forcalculating a P′ picture of a forward predictive coded image of apicture immediately preceding an I picture and the I picture.
 4. Amoving picture transmission apparatus comprising: moving picture datasupply means; moving picture data acquisition means for acquiringobjective moving picture data from said moving picture data supplymeans; data transmission means for transmitting the moving picture dataacquired by said moving picture data acquisition means to a transmissionline; basic image retention means being placed between said movingpicture data supply means and said data transmission means for retainingI pictures; and differential data calculation means being placed betweensaid moving picture data supply means and said data transmission meansfor calculating a P″ picture of a forward predictive coded image of an Ipicture immediately preceding the current I picture and the current Ipicture.
 5. A moving picture transmission apparatus comprising: movingpicture data supply means; moving picture data acquisition means foracquiring objective moving picture data from said moving picture datasupply means; data transmission means for transmitting the movingpicture data acquired by said moving picture data acquisition means to atransmission line; and differential data transmission means fortransmitting redundant data.
 6. A moving picture transmission apparatuscomprising: moving picture data supply means; moving picture dataacquisition means for acquiring objective moving picture data from saidmoving picture data supply means; data transmission means fortransmitting the moving picture data acquired by said moving picturedata acquisition means to a transmission line; and time informationaddition means for adding the same time information as the movingpicture data to redundant data.
 7. A moving picture transmissionapparatus comprising: moving picture data supply means; moving picturedata acquisition means for acquiring objective moving picture data fromsaid moving picture data supply means; data transmission means fortransmitting the moving picture data acquired by said moving picturedata acquisition means to a transmission line; and redundancy controldata reception means for receiving redundancy control data.
 8. A movingpicture reception means comprising: data reception means for receivingmoving picture data from a transmission line; decoding means fordecoding the moving picture data received by said data reception meansinto an image; display means for displaying the image provided by saiddecoding means; and error recovery means being placed between said datareception means and said decoding means for executing error recovery byusing a P′ picture of a forward predictive coded image of a pictureimmediately preceding an I picture and the I picture.
 9. A movingpicture reception means comprising: data reception means for receivingmoving picture data from a transmission line; decoding means fordecoding the moving picture data received by said data reception meansinto an image; display means for displaying the image provided by saiddecoding means; basic image retention means being placed between saiddata reception means and said decoding means for retaining I pictures;and error recovery means being placed between said data reception meansand said decoding means for executing error recovery by using a P″picture of a forward predictive coded image of an I picture immediatelypreceding the current I picture and the current I picture.
 10. A movingpicture reception means comprising: data reception means for receivingmoving picture data from a transmission line; decoding means fordecoding the moving picture data received by said data reception meansinto an image; display means for displaying the image provided by saiddecoding means; and differential data reception means for receivingredundant data.
 11. A moving picture reception means comprising: datareception means for receiving moving picture data from a transmissionline; decoding means for decoding the moving picture data received bysaid data reception means into an image; display means for displayingthe image provided by said decoding means; and redundant data separationmeans for separating redundant data from the data received by said datareception means based on time information.
 12. A moving picturereception means comprising: data reception means for receiving movingpicture data from a transmission line; decoding means for decoding themoving picture data received by said data reception means into an image;display means for displaying the image provided by said decoding means;and redundancy control data transmission means for transmittingredundancy control data.